A problem in laser-generated plasma research with large Q-switched lasers is premature disruption of targets by the long amplified spontaneous (i.e., "superradiance") prepulse that is delivered to the target before the arrival of the main pulse. A typical multistage neodymium-doped glass laser operating in the 100 joule per nanosecond mode emits a 1-joule superradiance precursor over about 10.sup..sup.-4 seconds. This is sufficient to destroy many experiments. For example, most targets designed to be heated to the several keV temperature regime upon absorption of the 100 joule main pulse will be vaporized and dispersed from the focal volume if struck by as little as about 0.01 joule of superradiance.
The superradiance could be suppressed by introducing a Kerr or Pockels cell shutter after or before the last stage. The shutter would block the superradiance but be switched on just before the main pulse arrives. Unfortunately, the construction of sufficiently large Kerr or Pockels cells is difficult and expensive, and for the case of large aperture disk lasers is totally impractical.
Methods and apparatus according to the present invention are advantageous for suppressing undesired precursors in high power Q-switched lasers of any aperture and in various other radiation sources.